Method of and apparatus for recording data on optical recording medium

ABSTRACT

A method of and apparatus for recording data on an optical recording medium form a mark or a space by using a recording waveform having an erase pattern containing a multi-pulse. The method and the apparatus prevent distortion of the mark or the space and improve a mark shape such that a recording/reproducing characteristic of the optical recording medium is improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Korean Patent ApplicationNos. 2001-61039, filed Sep. 29, 2001, and 2001-80541, filed Dec. 18,2001, in the Korean Intellectual Property Office, and U.S. ProvisionalApplication Nos. 60/327,305, filed Oct. 9, 2001, and 60/373,377, filedApr. 18, 2002, the disclosures of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a method of and apparatus forrecording data on an optical recording medium, and more particularly, toa method and apparatus in which digital data is recorded on an opticaldisc by forming a mark on the optical disc.

[0004] 2. Description of the Related Art

[0005] Data are recorded on an optical disc which is one type of opticalrecording media, in a form of a mark on a track formed on the opticaldisc. A mark is formed as a pit in a read-only disc, such as a CompactDisc-Read Only Memory (CD-ROM) and a Digital Versatile Disc-Read OnlyMemory (DVD-ROM). In a recordable disc, such as a CD-R/RW and aDVD-R/RW/RAM, a phase-change film which is changed into a crystallinephase or an amorphous phase is formed on a recording layer, and a markis formed by a phase change of the phase-change film.

[0006] Methods of recording data can be divided into a mark edgerecording method and a mark position recording method. According to themark position recording method, a signal of an amplitude of a detectedRadio Frequency (RF) signal is changed from negative to positive or frompositive to negative at a location on which a mark is recorded.According to the mark edge recording method, the signal of the amplitudeof the detected RF signal is changed from negative to positive or frompositive to negative at both edges of the mark. Therefore, recording theedges of the mark is an important factor in improving quality of asignal reproduced from the optical disc.

[0007] However, in a disc on which the phase-change film is coated, itis shown that a shape of a trailing edge of the mark recorded accordingto a prior art recording method changes according to a length of themark or an interval between the marks, i.e., a space. That is, thetrailing edge of the mark is formed greater than a leading edge of themark such that recording/reproducing characteristics of the disc aredegraded. If a recording mark is relatively long, therecording/reproducing characteristics are more degraded.

[0008] FIGS. 1A-1E are reference diagrams of recording waveforms (a),(b), and (c) to record a Non Return to Zero Inverted (NRZI) data signalaccording to the prior art. The recording waveform (a) is used forrecording the NRZI data signal on a DVD-RAM, the recording waveforms (b)and (c) are for a DVD-RW. Here, T denotes a cycle of a reference clock.According to the mark edge recording method, a high level of NRZI datais recorded as a mark and a low level of NRZI data is formed as a space.A portion of the recording waveform used in recording the mark isreferred to as a recording pattern, and another portion of the recordingwaveform used in forming the space (in erasing the mark) is referred toas an erase pattern. The prior art recording waveforms (a), (b) and (c)use a multi-pulse as the recording pattern, and a power of the erasepattern is maintained constant in a predetermined DC level for aninterval E as shown in FIG. 1E.

[0009] Since the DC level of the erase pattern included in the prior artrecording waveform is maintained constant for a predetermined period oftime, 0˜200° C. heat is continuously applied to an corresponding area toform the space. Therefore, if recording is repeatedly performed, a shapeof the mark is degraded and distorted such that therecording/reproducing characteristics of the optical disc are degraded.In particular, a development toward a high density and a high line speedfor recording more data on the optical disc makes the clock cycle Tshorter, and therefore a heat interference between pulses forming therecording waveform increases to cause more degradation of therecording/reproducing characteristics of the optical disc.

[0010] Meanwhile, in the prior art, the different recording waveformsare used according to the kinds of the optical discs and specifications,such as DVD-RAM and DVD-RW, because characteristics of recording filmsof the optical discs are different. In particular, due to the fact thatthe different recording waveforms should be used for each kind of theoptical discs, a problem occurs in manufacturing a multi-drive which canrecord/reproduce all specifications of the optical discs because themulti-drive should accommodate a variety of the different recordingwaveforms. The problem causes an increase in cost.

SUMMARY OF THE INVENTION

[0011] To solve the above and other problems, it is an object of thepresent invention to provide a recording method and apparatus in whichdistortion of shapes of a leading edge and a trailing edge of a mark anddegradation of the mark caused by repeated recording operations can beprevented.

[0012] It is another object of the present invention to provide arecording method and apparatus in which data is recorded by a recordingwaveform having an erase pattern which can improve a shape of a mark ora space.

[0013] It is yet another object of the present invention to provide arecording method and apparatus in which data is recorded by a recordingwaveform which can be applied to a disc having a recording film with avariety of characteristics.

[0014] Additional objects and advantageous of the invention will be setforth in part in the description which follows and, in part, will beobvious from the description, or may be learned by practice of theinvention.

[0015] To accomplish the above and other objects of the presentinvention, there is provided a method of recording data on an opticalrecording medium. The method includes forming a mark or a space by usinga recording waveform having an erase pattern containing a multi-pulse.

[0016] According to an aspect of the present invention, data is recordedaccording to a Run Length Limited (RLL) (2, 10) process in which 2 and10 are a minimum length and a maximum length of the mark or space,respectively, a first level of a predetermined Non Return to ZeroInverted (NRZI) data signal is recorded as the mark, and a second levelof the predetermined NRZI data signal is recorded as the space.

[0017] Also, to accomplish the above and other objects of the presentinvention, there is provided a method of recording data on the opticalrecording medium. The method includes generating a channel modulateddigital data (NRZI data) signal, generating the recording waveformhaving the erase pattern containing the multi-pulse and the recordingpattern, and forming the first level of the charnel modulate digitaldata signal as the mark and forming the second level of the channelmodulate digital data signal as the space by using the generatedrecording waveform.

[0018] According to an aspect of the present invention, the method isbased on the Run Length Limited (RLL) (2, 10) or RLL (1, 7) process inwhich 1 and 7 are the minimum length and the maximum length of the markor space.

[0019] According to another aspect of the present invention, a powerlevel of a leading pulse of the erase pattern is a low level of themulti-pulse and another power level of a trailing pulse is a high levelof the multi-pulse. Alternatively, the power level of the leading pulseof the erase pattern may be the high level of the multi-pulse, and thepower level of the trailing pulse may be the high level of themulti-pulse. The power level of the leading pulse of the erase patternmay be the low level of the multi-pulse and the power level of thetrailing pulse may be the low level of the multi-pulse. The power levelof the leading pulse of the erase pattern may be the high level of themulti-pulse and the power level of the trailing pulse may be the lowlevel of the multi-pulse.

[0020] According to another aspect of the present invention, a ratio ofa duration time of the high level and another duration time of the lowlevel of the multi-pulse is substantially 1:1, and the duration time ofthe high level is half a clock cycle.

[0021] It is possible that in the generating of the channel modulateddigital data, the first level of the NRZI data signal is formed as themark, and in the generating of the recording waveform, the second levelof the NRZI data signal is formed as the space.

[0022] The recording waveform includes a cooling pulse, and the erasepattern includes a part of the cooling pulse. It is possible that if anending time of the cooling pulse is less than or greater than 0.5 Tsfrom the trailing edge of the NRZI data, the duration time of theleading pulse forming the erase pattern increases over 0.5 Ts when T isa cycle of a reference clock signal.

[0023] According to another aspect of the present invention, a unitpulse constituting or included in the multi-pulse has a high level and alow level that are adjusted by the duration time of the leading pulse ofthe recording pattern.

[0024] According to another aspect of the present invention, therecording pattern has at least two power levels.

[0025] Also, to accomplish the above and other objects of the presentinvention, there is provided an apparatus for recording data on theoptical recording medium. The apparatus includes a recording waveformgenerating unit which generates the recording waveform having the erasepattern containing the multi-pulse and the recording pattern, and apickup unit which applies light to the optical recording mediumaccording to the generated recording waveform so that the mark or thespace is formed.

[0026] According to another aspect of the present invention, theapparatus also includes a channel modulation unit whichchannel-modulates input data received from an outside source and outputsthe generated NRZI data signal to the recording waveform generatingunit.

[0027] According to another aspect of the present invention, the pickupunit includes a motor which rotates the optical recording medium, anoptical head which applies a laser beam to the optical recording mediumor receives the laser beam reflected from the optical recording medium,a servo circuit which servo-controls the motor and the optical head, anda laser driving circuit which drives a laser device installed in theoptical head to generate the laser beam.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above objects and advantages of the present invention willbecome more apparent and more readily appreciated from the followingdescription of the preferred embodiments, taken in conjunction with theaccompanying drawings of which:

[0029] FIGS. 1A-1E are reference diagrams of recording waveformsaccording to the prior art;

[0030]FIG. 2 is a block diagram of a recording apparatus according to anembodiment of the present invention;

[0031]FIG. 3 shows an example of an implementation of the recordingapparatus of FIG. 2;

[0032] FIGS. 4A-4C show an example of a waveform generated by arecording waveform generating circuit of the recording apparatus of FIG.3;

[0033] FIGS. 5A-5C show another example of a waveform generated by therecording waveform generating circuit of the recording apparatus of FIG.3;

[0034]FIGS. 6A through 6E are waveforms explaining four types of erasepatterns according to another embodiment of the present invention;

[0035]FIGS. 7A and 7D are other examples of the erase pattern of FIG.6B;

[0036]FIGS. 8A through 10C are shapes of marks recorded in a simulation;

[0037]FIGS. 11A through 15 are graphs showing characteristics of aDVD-RAM;

[0038]FIGS. 16A through 20 are graphs showing characteristics of aDVD-RW; and

[0039]FIG. 21 is a flowchart showing a recording method according toanother embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Reference will now be made in detail to the present preferredembodiments of the present invention, examples of which are illustratedin the accompanying drawings, wherein like reference numerals refer tothe like elements throughout. The embodiments are described in order toexplain the present invention by referring to the figures.

[0041]FIG. 2 is a block diagram of a recording apparatus according to anembodiment of the present invention. Referring to FIG. 2, the recordingapparatus which forms a mark or a space on an optical recording medium(optical disc) 200, has a pickup unit 1, a recording waveform generatingcircuit 2, and a channel modulator 3.

[0042] The channel modulator 3 modulates input data which is input froman outside source into a channel bit stream, such as a Non Return toZero Inverted (NRZI) data signal. The recording waveform generating unit2 receives the channel bit stream and generates a recording waveform torecord the received channel bit stream. The recording waveform generatedaccording to the embodiment of the present invention has an erasepattern having an erase multi-pulse. The recording waveform will beexplained later in detail. The pickup unit 1 applies light (a laserbeam) to the optical recording medium 1 according to the generatedrecording waveform so as to form the mark or the space.

[0043]FIG. 3 shows an example of an implementation of the recordingapparatus of FIG. 2. The same blocks will be indicated by the samereference numerals, and the same explanation will be omitted. Referringto FIG. 3, the recording apparatus includes the pickup unit 1, therecording waveform generating circuit 2, and the channel modulator 3.The pickup unit 1 has a motor 11 rotating the optical disc 200, anoptical head 13 receiving the light reflected from the optical disc 200,a servo circuit 12 controlling the motor and the optical head, and alaser driving circuit 14 driving a laser device (not shown) installed inthe optical head 13 to generate the light.

[0044] The channel modulator 3 modulates the input data into the channelbit stream and outputs the NRZI data signal. The recording waveformgenerating circuit 2 generates the recording waveform to record the NRZIdata signal and provides the recording waveform to the laser drivingcircuit 14. The laser driving circuit 14 forms the mark or the space bycontrolling the laser device in accordance with the received recordingwaveform.

[0045] FIGS. 4A-4C show an example of the recording waveforms generatedby the recording waveform generating circuit 2. Referring to FIGS.4A-4C, the NRZI data signal is changed from the input data according toa modulation method of the channel modulator 3. That is, if themodulation method is a Run Length Limited (RLL) (2, 10) series method.That is, according to an Eight to Fourteen Modulation (EFM) method, anEight to Fourteen Modulation plus (EFM+) method, a D(8-15) method, and aDual modulation method, a minimum length of the mark or the space is 3Ts and a maximum length of the mark or the space is 11 Ts, where T is acycle of a clock signal as shown in FIG. 4A, The D(8-15) method is amodulation method disclosed in “Optical Disc Recording System of 25 GBCapacity” announced by Matsushita in Optical Data Storage (ODS) 2001.The Dual modulation method is disclosed in Korean Patent Application No.99-42032 titled “An RLL code allocation method, modulation anddemodulation method, and demodulation apparatus having improved DCcontrolling capability,” filed by the present applicant on Sep. 30,1999, and published on Nov. 25, 2000. If data is recorded using theRLL(1, 7) series method, the minimum length is 2 Ts, and the maximumlength is 8 Ts.

[0046] When a high level of the NRZI data signal is formed as the markand a low level of the NRZI data signal is formed as the space, therecording waveform includes a recording pattern to record a mark of a 7T length, an erase pattern to form a space of a 3 T length, and anotherrecording pattern to record a mark of a 3 T length as shown in FIG. 4B.

[0047] The recording pattern includes a pulse train, e.g., amulti-pulse. Also, the erase pattern is formed with another pulse train,e.g., another multi-pulse (erase multi-pulse) having an interval F asshown in FIG. 4C. Tmp indicates a width of a pulse of the multi-pulse ofthe recording pattern. Here, the multi-pulse indicates at least onepulse having the same width and power. However, it is understood thatthe present invention is not limited thereto. That is, the width and thepower of the each pulse of the multi-pulse may vary. In the presentembodiment, Tmp is 0.5 Ts. Tip indicates a width of a last pulse of therecording pattern. Tcl indicates a width (duration time) of a coolingpulse. The cooling pulse extends from the recording pattern to the erasepattern. Temp indicates a width of a pulse of the multi-pulse of theerase pattern. In the present embodiment, Temp is 0.5 Ts. Tsfp indicatesa period from a point where the NRZI data signal is transited from thelow level to the high level at a point (start point of a first pulse)when the first pulse forming the recording pattern starts. Tsfp is underan influence of a power level of the erase pattern. That is, as shown inFIG. 4C, if Tsfp is greater than 0.5 Ts and the multi-pulse contained inthe erase pattern ends at low level Pb1, a next Tsfp starts from a highlevel Pb2 of the multi-pulse. Meanwhile, if Tsfp is less than 0.5 Ts andthe multi-pulse contained in the erase pattern ends at a low level Pb1,the next Tsfp maintains the low level Pb1 of the multi-pulse.

[0048] FIGS. 5A-5C show another example of waveforms generated by therecording waveform generating circuit 2. Referring to FIG. 5B, when thehigh level of the NRZI data signal is formed as the mark, and the lowlevel is formed as the space, the recording waveform includes therecording pattern to record a mark of a 7 T length, the erase pattern toform a space of a 5 T length, and the recording pattern to record a markof a 3 T length.

[0049] The recording pattern includes the pulse train. Also, the erasepattern is formed with the pulse train, e.g., the multi-pulse (erasemulti-pulse) having an interval G as shown in FIG. 5C. Tmp indicates thewidth of the multi-pulse forming the recording pattern. Here, themulti-pulse indicates at least one pulse having the same width andpower. However, it is understood that the present invention is notlimited thereto. That is, the width and the power of the each pulse ofthe multi-pulse may vary. In the present embodiment, Tmp is 0.5 Ts. Tlpindicates the width of the last pulse forming a recording pattern. Tclindicates the width (duration time) of the cooling pulse. The coolingpulse extends from the recording pattern to the erase pattern. Tempindicates the width of the erase multi-pulse constituting the erasepattern. In the present embodiment, Temp is 0.5 Ts. Tsfp indicates aperiod from a point where the NRZI data is transited from the low levelto the high level at the point (start point of the first pulse) when thefirst pulse constituting the recording pattern starts. Tsfp isdetermined in response to the power level of the erase pattern. That is,as shown in FIG. 5C, if Tsfp is greater than 0.5 Ts and the multi-pulsecontained in the erase pattern ends at low level Pb1, the next Tsfpstarts from the high level Pb2 of the multi-pulse. Meanwhile, if Tsfp isless than 0.5 Ts and the multi-pulse contained in an erase pattern endsat the low level Pb1, the next Tsfp maintains the low level Pb1 of themulti-pulse.

[0050]FIGS. 6A through 6E are waveforms explaining four types of theerase patterns according to another embodiment of the present invention.Referring to FIGS. 6A through 6d 6E, the erase patterns are divided intothe four types: (a) LH, (b) HH, (c) HL, and (d) LL. Differences betweenthe power levels of the erase patterns are marked with circles so thatthe differences can be easily understood as shown in FIGS. 6B through6E.

[0051] First, the (a) LH indicates that a power of a leading pulse ofthe erase pattern is the same as the low level Pb1 of the followingpulse of the erase multi-pulse, and when a last pulse of the erasemulti-pulse of the erase pattern ends at the low level Pb1, the powerlevel of the following Tsfp is the same as the high level Pb2 of theerase multi-pulse. The (b) HH indicates that the power of the leadingpulse forming the erase pattern is the same as the high level Pb2 of thefollowing pulse of the erase multi-pulse, and when the last pulse of theerase multi-pulse of the erase pattern ends at the high level Pb2, thelevel of the following Tsfp continues to be the same high level Pb2 ofthe erase multi-pulse. The (c) HL indicates that the power of theleading pulse forming the erase pattern is the same as the high levelPb2 of the following pulse of the erase multi-pulse, and when the lastpulse of the erase multi-pulse of the erase pattern ends at the highlevel Pb2, the level of the following Tsfp is the same as the low levelPb1 of the erase multi-pulse. Finally, the (d) LL indicates that thepower of the leading pulse forming the erase pattern is the same as thelow level Pb1 of the following pulse of the erase multi-pulse, and whenthe last pulse of the erase multi-pulse of the erase pattern ends at thelow level Pb1, the level of the following Tspf continues to be the samelow level Pb1 of the erase multi-pulse.

[0052]FIGS. 7A and 7D are other examples LH2 and LH3 of LH of FIG. 6B.Referring to FIGS. 7A and 7D, the (e) LH2 is the same as (a) LH of FIG.6B, except that Temp1, a duration time of the high level Pb2 of themulti-pulse forming a cycle, is 0.7 Ts and Temp2, a duration time of thelow level Pb1 of the multi-pulse, is 0.3 Ts. Also, the (f) LH3 is thesame as (a) LH of FIG. 6B, except that the duration time of the highlevel Pb2 or the low level Pb1 of the multi-pulse is 1.0 T. Here, aratio of Temp1 and Temp2, that is, the ratio of the duration time of thehigh level Pb2 and that of the low level Pb1 of the multi-pulse forminga cycle can be changed as m:n in a variety of ways. (Here, m and n areintegers.) Thus, the recording waveform according to the presentinvention has the erase pattern containing the multi-pulse (erasemulti-pulse) of which power is the high level Pb2 or the low level Pb1,and therefore distortion of the trailing edge of the mark is preventedand the reproducing characteristic of the optical disc is improved. Inparticular, in the recording waveforms shown in the embodimentsdescribed above, the duration time of the high level Pb2 and the lowlevel Pb1 of the multi-pulse is adjusted within a range between 0.25 Tsand 0.75 Ts for a clock cycle T, and a duration time appropriate to heatcharacteristic of the optical disc 200 is selected. Therefore, thereproducing characteristic of the optical disc is more improved.

[0053] Meanwhile, information on the four types of the erase patterns(type information) may be recorded in a lead-in area of a recordabledisc (optical disc) or may be included in a wobble signal as one ofheader information items. In this case, when data are recorded, therecording apparatus reads type information from the lead-in area or fromthe wobble signal to form the mark or the space by generating acorresponding recording waveform.

[0054] In addition, the four types of the erase patterns may be used asa symbol indicating multiple times speed of the disc or the kind of themark when data is recorded and reproduced. For example, the erasepattern may indicate information of “the speed of a disc using LH typeerase pattern is 20-multiple times speed.”

[0055] In order to test an effect of the present invention, shapes ofthe mark recorded in a simulation were observed. A structure used in thesimulation is shown in table 1. The disc used in the simulation has a4-layered film structure. TABLE 1 Dielectric Recording DielectricReflecting Substrate film film film film Material PC ZnS-SiO₂ Sb-TeZnS-SiO₂ Ag alloy eutectic Thickness 0.6 mm 128 nm 14 nm 16 nm 30 nm

[0056] Each condition of the simulations includes a wavelength of 405nm, a numeral aperture (NA) of 0.65, and a linear velocity of 6 m/s. Inorder to observe the shape of the mark, after a recording mark of 8 T isrecorded, a next recording mark of 8 T is recorded by overlapping 4 T ofthe previous recording mark of 8 T. FIGS. 8A through 10C show comparisonresults between the mark shapes when the prior art recording waveformwas used and the mark shapes when the recording waveform according tothe present invention was used. FIG. 8A, shows a mark (a) formed by thesimulation, FIG. 8B shows a mark (b) formed on the mark (a) by arecording waveform according to the present invention, and FIG. 8C showsa mark (c) formed on the mark (a) by the prior art recording waveform.Likewise, FIG. 9A shows a mark (d) formed by the simulation, FIG. 9Bshows a mark (e) formed by the recording waveform having the erasepattern according to the present invention, and FIG. 9C shows a mark (f)formed by the recording waveform having the prior art DC erase pattern.FIG. 10A shows a mark (g) formed by the simulation, FIG. 10B shows aresult of erasing the mark (g) by the erase pattern according to thepresent invention, and FIG. 10C shows a result of erasing the mark (g)by the prior art DC erase pattern.

[0057] Table 2 shows parameters of thin films of the optical disc usedin another simulation for interpreting heat. TABLE 4 λ = 405 nm Materialn K C(J/cm³K) k(W/cmK) ZnS-SiO₂ 2.300 0.000 2.055 0.0058 Sb-Te eutectic1.650 3.150 1.285 0.0060 (Crystal) Sb-Te eutectic 2.900 2.950 1.2850.0060 (Amorphous) Ag alloy 0.170 2.070 2.450 0.2000

[0058] Referring again to simulation results of FIGS. 8A through 10C, itis shown that the trailing edge of the mark (b) formed by the recordingwaveform having the erase pattern according to the present invention asshown in FIG. 8B is better than the trailing edge of the mark (c) formedby the recording waveform having the prior art DC erase pattern of theprior art method as shown in FIG. 8C. Like the trailing edges, the shapeof the leading edge of the mark is better when the erase patternaccording to the present invention as shown in FIG. 9B. The results ofthe simulation show that the shape of the mark when the recordingwaveform having the erase pattern formed with the erase multi-pulse isused, is improved compared with the prior art. By adjusting the shape,width, and power level of the erase multi-pulse, distortion of the shapeof the mark can be more reduced.

[0059] In order to experimentally verify the effect of the presentinvention, parameters needed in obtaining the recording waveforms shownin FIGS. 4A through 5C, that is, the duration time and the power level,were obtained from 4.7 GB DVD-RAM and 4.7 GB DVD-RW disc using a DVDevaluator of which the laser wavelength is 650 nm and the NA is 0.60.Then, characteristics of repetitive recording/reproducing the NRZI datasignal according to the present invention were compared with the priorart method.

[0060]FIGS. 11A through 15 are graphs showing the characteristics of theDVD-RAM. FIGS. 11A through 13B show features of power and time ofrecording the NRZI data signal using the recording waveform with the DCerase pattern of the prior art, and FIGS. 14A, 14B, and 15 show improvedfeatures of recording the NRZI data signal using the recording waveformof the present invention. FIGS. 11A and 11B show jitter characteristicswith respect to recording power and erase power, respectively, for theleading edge, trailing edge, and both edges of the mark in the prior artDC erase. Based on the jitter characteristics, 14.5 mW recording powerand 6 mW erase power were selected for experiments.

[0061]FIGS. 12A through 13B show the measured results in the prior artDC erase. Referring to FIGS. 12A-12G and of FIG. FIGS. 13A and 13B, themost preferable jitter characteristics are shown when Tsfp=0.5 Ts andwhen Tsfp=0.4 Ts. Tcl didn't affect the jitter characteristics, and Tlpwas good when the cycle is 0.7 Ts.

[0062] Based on the parameters experimentally obtained in this way, themark was formed with the recording waveform having the four types oferase patterns described above, and the characteristics of the formedmark were measured as the following.

[0063]FIGS. 14A and 14B show the jitter characteristics of the fourtypes according to the present invention shown in FIG. 6. Referring toFIGS. 14A and 14B, it can be inferred that jitter characteristic is goodwhen the NRZI data signal is recorded using the recording waveform withthe erase pattern, i.e., any one of the four types of the erase patternshown in FIGS. 6A-6E, of the present invention. Especially, referring toFIG. 14A, it is shown that the LH type is the best among the four types.Referring to FIG. 14B, when the erase pattern formed with the erasemulti-pulse according to the present invention is used in erasing themark, the jitter characteristics of ΔPb (Pb2-Pb1), which is a differencebetween the high level and the low level of the erase multi-pulse, isshown. It is shown that up to 5 mWs there is no big difference.

[0064]FIG. 15 shows the jitter characteristics of the results ofrepetitive recording/reproducing using the recording waveform having theerase pattern according to the present invention compared with the priorart. Referring to FIG. 15, it is easily understood that when the mark iserased using the erase multi-pulse according to the present invention,the result is good, especially in the repetitive recordingcharacteristics aspect.

[0065]FIGS. 16A through 20 are graphs showing characteristics of theDVD-RW. FIGS. 16A through 18B show features of power and time ofrecording the NRZI data signal using the recording waveform with the DCerase pattern of the prior art, and FIGS. 19A through 20 show improvedfeatures of recording the NRZI data signal using the recording waveformof the present invention.

[0066]FIGS. 16A and 16B show jitter characteristics with respect torecording power and erase power, respectively, for the leading edge,trailing edge, and both edges of the mark in the prior art DC erase.Based on FIGS. 16A and 16B, 14.0 mW recording power and 6mW erase powerwere selected.

[0067]FIGS. 17A through 18B show the measured results in the prior artDC erase. Referring to FIGS. 17A through 18B, the most preferable jittercharacteristics are shown when Tsfp=0.3 Ts and when Tsfp=0.05 Ts. Tclwas good in 0.55 Ts, and Tlp was good in 1.0 T and 1.1 Ts.

[0068] Based on the parameters experimentally obtained in this way, themark was formed with the recording waveform having the four types oferase patterns described above, and the reproducing characteristics ofthe formed mark were measured as the following.

[0069]FIGS. 19A and 19B show the jitter characteristics of the fourtypes shown in FIGS. 6B through 6E. Referring to FIG. 19A, it is shownthat the LH type is the best among the four types. When the erasepattern formed with the erase multi-pulse according to the presentinvention is used in erasing the mark, the jitter characteristics ofΔPb(Pb2-Pb1) which is the difference between the high level and the lowlevel of the erase multi-pulse is shown. Since the characteristics aresuddenly degraded from 3 mW, 1 mW was selected as a condition for therepetitive recording/reproducing experiment.

[0070]FIG. 20 shows the jitter characteristics of the results ofrepetitive recording/reproducing the NRZI data signal using therecording pulse having the erase pattern according to the presentinvention. Referring to FIG. 20, it is easily understood that when themark is erased using the erase multi-pulse according to the presentinvention, the result is good, especially in the repetitive recordingcharacteristics aspect. However, the jitter characteristics weresuddenly degraded from 2,000 times. Therefore, it is shown that thepulse erase method according to the present invention is advantageous upto 1,000 times repetitive recording that is guaranteed in the normalDVD-RW.

[0071] Meanwhile, the above experiments followed the DVD formats andtherefore the EFM+ modulation method was used. However, if any of othermodulation methods that are normally used, for example, the RLL(1, 7)method, the D(8-15) method, and the Dual modulation method, is used, theresult will be the same.

[0072] A recording method according to another embodiment of the presentinvention based on the structure described above will now be explained.

[0073]FIG. 21 is a flowchart showing the recording method. Referring toFIG. 21, the recording apparatus receives data from the outside source,modulates the data, and generates the NRZI data signal in operation1801. Then, the recording apparatus generates the recording waveformhaving the erase pattern containing the erase multi-pulse in operation1802. Using the generated recording waveform, the mark or the space isformed on the optical disc 200 in operation 1803.

[0074] As described above, according the present invention, the methodof and apparatus for recording data using the recording waveformprevents distortion of the shape of the mark occurring due to a heatinterference and a heat accumulation when data is recorded, and improvesthe shape of the mark so that the characteristics ofrecording/reproducing of the data are improved.

[0075] Although a few preferred embodiments of the present inventionhave been shown and described, it would be appreciated by those skilledin the art that changes may be made in this embodiment without departingfrom the principles and sprit of the invention, the scope of which isdefined in the claims and their equivalents.

What is claimed is:
 1. A method of recording data on an opticalrecording medium, the method comprising: forming a mark or a space byusing a recording waveform having an erase pattern containing amulti-pulse.
 2. The method of claim 1, wherein the forming of the markor the space comprises: recording data according to a Run Length Limited(RLL)(2, 10) method.
 3. The method of claim 1, wherein the forming ofthe mark or the space comprises: recording a first level of a Non Returnto Zero Inverted (NRZI) data signal as a mark and a second level of theNRZI data signal as the space.
 4. A method of recording data on anoptical recording medium, the method comprising: generating channelmodulated digital data; generating a recording waveform having an erasepattern containing a multi-pulse and a recording pattern in response tothe channel modulated digital data; and forming a first level of thechannel modulated digital data as a mark and forming a second level ofthe channel modulated digital data as a space by using the generatedrecording waveform.
 5. The method of claim 4, wherein the generating ofthe channel modulated digital data comprises: performing a Run LengthLimited (RLL)(2, 10) method.
 6. The method of claim 4, wherein thegenerating of the channel modulated digital data comprises: performing aRun Length Limited RLL(1, 7) method.
 7. The method of claim 4, whereinthe generating of the recording waveform comprises: causing a powerlevel of a leading pulse of the erase pattern to be a low level of themulti-pulse and a power level of a trailing pulse of the erase pulse tobe a high level of the multi-pulse.
 8. The method of claim 4, whereinthe generating of the recording waveform comprises: causing a powerlevel of a leading pulse of the erase pattern to be a high level of themulti-pulse and a power level of a trailing pulse to be a high level ofthe multi-pulse.
 9. The method of claim 4, wherein the generating of therecording waveform comprises: causing a power level of a leading pulseof the erase pattern to be a low level of the multi-pulse and a powerlevel of a trailing pulse to be a low level of the multi-pulse.
 10. Themethod of claim 4, wherein the generating of the recording waveformcomprises: causing a power level of a leading pulse of the erase patternto be a high level of the multi-pulse and a power level of a trailingpulse to be a low level of the multi-pulse.
 11. The method of claim 4,wherein the generating of the recording waveform comprises: causing aratio of a duration time of a high level and another duration time of alow level of the multi-pulse to be substantially 1:1.
 12. The method ofclaim 11, wherein the generating of the recording waveform comprises:causing the duration time of the high level to be half a clock cycle.13. The method of claim 11, wherein the generating of the recordingwaveform comprises: causing the ratio of the duration time of the highlevel and the duration time of the low level of the multi-pulse to bem:n where m and n are integers.
 14. The method of claim 4, wherein thegenerating of the channel modulated digital signal comprises: forming afirst level of an NRZI data signal as the mark and a second level of theNRZI data signal as the space.
 15. The method of claim 14, wherein thegenerating of the recording waveform comprises: forming a cooling pulseas a part of the erase pattern.
 16. The method of claim 15, wherein thegenerating of the recording waveform comprises: upon determining whetheran ending time of the cooling pulse is less than or greater than 0.5 Tsfrom a trailing edge of the NRZI data signal, causing a duration time ofa leading pulse forming the erase pattern to be over 0.5 Ts.
 17. Themethod of claim 16, wherein the generating of the recording waveformcomprises: forming a unit pulse of the multi-pulse to have a high leveland a low level that are adjusted by the duration time of the leadingpulse forming the recording pattern.
 18. The method of claim 4, whereinthe generating of the recording wave form comprises: forming therecording pattern having at least two power levels.
 19. An apparatus forrecording data on an optical recording medium, comprising: a recordingwaveform generating unit which generates a recording waveform having anerase pattern containing a multi-pulse and a recording patterncontaining another multi-pulse; and a pickup unit which generates lightto the optical recording medium according to the generated recordingwaveform so that a mark or a space is formed on the optical recordingmedium.
 20. The apparatus of claim 19, further comprising: a channelmodulation unit which channel modulates data provided from an outsidesource, and outputs an NRZI data signal to the recording waveformgenerating unit.
 21. The apparatus of claim 19, wherein the pickup unitcomprises: a motor which rotates the optical recording medium; anoptical head having a laser device which generates a laser beam to theoptical recording medium or receives the laser beam reflected from theoptical recording medium; a servo circuit which servo-controls the motorand the optical head; and a laser driving circuit which drives the laserdevice installed in the optical head.
 22. An apparatus for forming afirst state and a second state alternatively and sequentially on anoptical recording medium in response to input data having a first leveland a second level, respectively, in an optical recording apparatus,comprising: a recording waveform generating unit generating a recordingwaveform which includes a first multi-pulse having a plurality of firstpulses corresponding to the first level of the input data and a secondmulti-pulse having a plurality of second pulses corresponding to thesecond level of the input data.
 23. The apparatus of claim 22, furthercomprising: a pickup unit generating light to form the first state andthe second state on the optical recording medium in accordance with thefirst multi-pulse and the second multi-pulse of the recording waveformgenerated from the recording waveform generating unit.
 24. The apparatusof claim 23, wherein the pickup unit comprises: a laser devicegenerating the light varying in accordance with the first pulses of thefirst multi-pulse and the second pulses of the second multi-pulse toform the first state and the second state on the optical recordingmedium.
 25. The apparatus of claim 24, wherein the laser device has avoltage to generate the light, and the voltage varies according to thefirst pulses during forming the first state and in accordance with thesecond pulses during forming the second state.
 26. The apparatus ofclaim 24, wherein the voltage is not a DC voltage.
 27. The apparatus ofclaim 22, wherein the input data comprises NRZI data having a highpotential and a low potential each representing one of the first leveland the second level.
 28. The apparatus of claim 22, wherein the firststate is a mark, and the second state is a space.
 29. The apparatus ofclaim 22, wherein the first multi-pulse is a recording pattern to form amark, and the second multi-pulse is an erase pattern to form a space.30. The apparatus of claim 22, wherein the recording waveform generatingunit generates a cooling pulse extended from one of the first pulses ofthe first multi-pulse to one of second pulses of the second multi-pulse.31. The apparatus of claim 30, wherein the cooling pulse forms a portionof the first pulses and a portion of the second pulses.
 32. Theapparatus of claim 22, wherein the first pulses of the first multi-pulsehave a first high level and a first low level, and the second pulses ofthe second multi-pulse have a second high level and a second low level.33. The apparatus of claim 32, wherein the second high level of thesecond pulses is smaller than the first high level of the first pulses.34. The apparatus of claim 32, wherein the first pulses comprise a firststarting pulse and a first ending pulse, and the second pulses comprisea second starting pulse and an ending pulse, the first starting pulsevarying in accordance with the second starting pulse and the secondending pulse of the second pulses.
 35. The apparatus of claim 32,wherein the first pulses have a first duty cycle, and the second pulsesa second duty cycle.
 36. The apparatus of claim 35, wherein each secondpulse comprises a high level and a low level, and the second duty cyclecomprises: a ratio of a duration time of the high level and anotherduration time of the low level in a range between 0.25 T and 0.75 T,where T is a cycle of a reference clock.
 37. The apparatus of claim 22,further comprising: a servo unit rotating the optical recording mediumaccording to one of the first multi-pulse and the second multi-pulseduring forming the first state and the second state.
 38. The apparatusof claim 37, wherein the second multi-pulse comprises a starting pulseand an ending pulse, and the servo unit controls a rotation speed of theoptical recording medium in accordance of one of the starting pulse andthe ending pulse of the second multi-pulse.
 39. The apparatus of claim22, wherein the recording waveform generating unit generates informationdata representing a characteristic of the second multi-pulse.
 40. Theapparatus of claim 39, wherein the information data is recorded on theoptical recording medium as a wobble signal.
 41. The apparatus of claim39, further comprising: a servo unit rotating the optical recordingmedium in accordance with the information data.
 42. The apparatus ofclaim 39, further comprising: a laser device recording the informationdata on the optical recording medium.
 43. The apparatus of claim 42,wherein the optical recording medium comprises a lead-in-area, and theinformation data is recorded in the lead-in-area of the opticalrecording medium.
 44. The apparatus of claim 42, further comprising: aservo unit reading the information data from the optical recordingmedium and rotating the optical recording medium at a speedcorresponding to the information data.
 45. The apparatus of claim 42,further comprising: a servo unit rotating the optical recording mediumin a first speed, reading the information data from the opticalrecording medium, and rotating the optical recording medium at a secondspeed according to the information data.
 46. An apparatus for forming arecording pattern and an erase pattern alternatively and sequentially onan optical recording medium in response to input data having a firstlevel and a second level, respectively, in an optical recordingapparatus, comprising: a recording waveform generating unit generating arecording waveform which includes a first multi-pulse having a pluralityof first pulses to form the recording pattern in response to the firstlevel of the input data and a second multi-pulse having a plurality ofsecond pulses to form the erase pattern in response to the second levelof the input data.
 47. The apparatus of claim 46, wherein the recordingwaveform generating unit generates a cooling pulse as a portion of thefirst multi-pulse and another portion of the second multi-pulse.
 48. Theapparatus of claim 46, wherein the first pulses of the first multi-pulseeach have a first duty cycle and a first amplitude, and the secondpulses of the second multi-pulse each have a second duty cycle differentfrom the first duty cycle and a second amplitude different from thefirst height.
 49. The apparatus of claim 46, further comprising: apickup unit forming a mark corresponding to the recording pattern on theoptical disc in response to the first pulses of the first multi-pulseand erasing another mark to form a space corresponding to the erasepattern on the optical disc n response to the second pulses of thesecond multi-pulse.
 50. A method of forming a first state and a secondstate alternatively and sequentially on an optical recording medium inresponse to input data having a first level and a second level in anoptical recording apparatus, the method comprising: generating arecording waveform which includes a first multi-pulse having a pluralityof first pulses corresponding the first level of the input data and asecond multi-pulse having a plurality of second pulses corresponding tothe second level of the input data.
 51. The method of claim 50, furthercomprising: forming the first state on the optical recording mediumaccording to the first pulses of the first multi-pulse; and forming thesecond state on the optical recording medium according to the secondpulses of the second multi-pulse.
 52. The method of claim 50, furthercomprising: forming a mark as the first state on the optical recordingmedium according to the first multi-pulse; and forming a space as thesecond state on the optical recording medium according to the secondmulti-pulse.
 53. The method of claim 50, wherein the generating of therecording waveform comprises: changing the first multi-pulse accordingto a characteristic of the second pulses of the second multi-pulse. 54.The method of claim 50, wherein the second multi-pulse comprises astarting pulse and an ending pulse, and the changing of the firstmulti-pulse comprises: changing a starting pulse of the firstmulti-pulse according to a characteristic of one of the starting pulseand the ending pulse of the second multi-pulse.
 55. The method of claim54, wherein the changing of the starting pulse of the first multi-pulsecomprises: changing a voltage level of the starting pulse of the firstmulti-pulse.
 56. The method of claim 50, further comprising: generatinginformation data representing a characteristic of one of the firstmulti-pulse and the second multi-pulse.
 57. The method of claim 56,further comprising: rotating the optical recording medium in response tothe information data.
 58. The method of claim 56, further comprising:rotating the optical recording medium in response to the informationdata
 59. The method of claim 56, further comprising: recording theinformation data on the optical recording medium.